Please posts information regarding Kathipara flyover, Padi flyover etc in this thread. A lot has been said about these in the Project update, I wish someone would do a compilation of all that valuable info and cross post them here for easier reading. I myself am too lazy for it now lol

Chennai, March 29: The first bridge constructed by the present DMK regime to ease traffic in the city would be inaugurated by chief minister M. Karunanidhi on Sunday. The North Usman Road flyover, built on the intersection of Kodambakkam High Road and Mahalingapuram Road, at a cost of Rs 9.72 crore will reduce traffic bottlenecks in the Kodambakkam, Mahalingapuram and T. Nagar areas. On Saturday, state local administration minister M K Stalin inspected the flyover and reviewed the finishing touches on the spot. It is a two-way flyover running through a length of 472 mts with a width of 8 mts constructed in six months. Chennai mayor M Subramanian, corporation commissioner Rajesh Lakhoni and top civic officials were present with Mr Stalin during the inspection.

According to corporation sources, at least a dozen bridges would be completed in Chennai in the next two years. Traffic congestion in Kodambakkam and T. Nagar would ease by this October as constructions of four bridges are nearing completion. Designs are also ready for four new bridges at Madhya Kailash, Thiruvanmiyur, Mint junction and Basin Bridge, the sources said. The bridge in T. Nagar near Pothys junction would be ready by July. Piling works are underway at G N Chetty Road and this bridge would be inaugurated by October.CM to open Kodambakkam flyover

Chennai, March 29: The first bridge constructed by the present DMK regime to ease traffic in the city would be inaugurated by chief minister M. Karunanidhi on Sunday. The North Usman Road flyover, built on the intersection of Kodambakkam High Road and Mahalingapuram Road, at a cost of Rs 9.72 crore will reduce traffic bottlenecks in the Kodambakkam, Mahalingapuram and T. Nagar areas. On Saturday, state local administration minister M K Stalin inspected the flyover and reviewed the finishing touches on the spot. It is a two-way flyover running through a length of 472 mts with a width of 8 mts constructed in six months. Chennai mayor M Subramanian, corporation commissioner Rajesh Lakhoni and top civic officials were present with Mr Stalin during the inspection.

According to corporation sources, at least a dozen bridges would be completed in Chennai in the next two years. Traffic congestion in Kodambakkam and T. Nagar would ease by this October as constructions of four bridges are nearing completion. Designs are also ready for four new bridges at Madhya Kailash, Thiruvanmiyur, Mint junction and Basin Bridge, the sources said. The bridge in T. Nagar near Pothys junction would be ready by July. Piling works are underway at G N Chetty Road and this bridge would be inaugurated by October.CM to open Kodambakkam flyover

CHENNAI: Stalin to the incumbent M Subramanian, Chennai Corporation’s answer to traffic jams has always been flyovers and more flyovers.

Even as 11 flyover projects are already under way across the city, the Mayor announced three new flyovers - two in North Chennai and one in South - during the budget announcement on Wednesday.

In North , flyovers will be built at Cemetry Road-Washermenpet clock tower intersection and at Ganeshapuram railway subway, while in South , a flyover with a vehicular subway will be constructed at Thiruvanmiyur- Lattice Bridge Road intersection.

In addition, Chennaiites have reasons to cheer as the Mayor announced that 11 small bridges would be constructed across main waterways to connect residential settlements developed on the banks of these canals.

To ease traffic congestion at R K Mutt Road area, it has been planned to develop a new link road at Adyar, to connect Greenways Road and Durgabai Deshmukh Road via Music College campus, while a proposed four-lane road connecting Anna Nagar and Ayanavaram (New Avadi Road- Medavakkam Tank Road-Raju Naicker Road) will be carried out after acquiring land from Metrowater and Institute of Mental Health, Kilpauk, Subramanian added.

For the benefit of road users the Corporation has proposed to concretise 13 arterial roads in North Chennai.

Thanks for your effort in crossposting the flyover psts TechCity. Very kind of you

Very interesting link in the blog aswell. Thanks for sharing. I rcently highlighted the lane weaving issue which could potentialle be another problem as the loops in Kathipara becomes operational. The more the public are made aware of these, the harder it will be for planners and constructors to get away with poor and unsafe designs.

Thanks for your effort in crossposting the flyover psts TechCity. Very kind of you

Quote:

Originally Posted by Fusionist

Very interesting link in the blog aswell. Thanks for sharing. I rcently highlighted the lane weaving issue which could potentialle be another problem as the loops in Kathipara becomes operational. The more the public are made aware of these, the harder it will be for planners and constructors to get away with poor and unsafe designs.

Whatever issues we are talking,It should have happend for other countries also.
If the same issue is happening everywhere means,we cant blame govt for that.
Whether cloverleaf model bridges in other countries got success or not?

I want to know,which is wrong,the cloverleaf model,or our implemenation.

That blog is talking aboyt something "shoulder". That is good point.We are missing that.But lane weaving issue is possible in all cloverleaf model bridges,right.

Whatever issues we are talking,It should have happend for other countries also.
If the same issue is happening everywhere means,we cant blame govt for that.
Whether cloverleaf model bridges in other countries got success or not?

I want to know,which is wrong,the cloverleaf model,or our implemenation.

That blog is talking aboyt something "shoulder". That is good point.We are missing that.But lane weaving issue is possible in all cloverleaf model bridges,right.

I think there are problems with the cloverleaf model itself but a lot more can be added if it is poorly implemented. Cloverleafs necessarily have weaving, but if the size of the cloverleaf itself is large and the loops spaced apart, and if the volume of traffic in the loops is relatively less, then the cloverleaf would suffice.

In Kathipara's case the flow of high volume traffic is a bit different. There is high volume of traffic on the Airport to Anna Salai sector and by the present u/c flover it has to use the loop after havbing to 'weave' across the traffic from Anna Salai to IRR which is the problem area.

For example here is an idea of how the cloverleafs are being handled in the US & UK..

Quote:

A point of conflict is the merging of exiting and entering traffic in the same lane, known as weaving. Most road authorities have since been implementing new interchange designs with more straight exit ramps that do not result in weaving. These interchanges include the diamond, parclo and Single-point urban (SPUI) interchanges when connecting to an arterial road, and the stack or cloverstack when connecting to another freeway or to a busy arterial where signals are still not desired.

Not only is this true for new interchanges but it also holds when existing cloverleaf interchanges are upgraded. In Norfolk, Virginia, the interchange between U.S. 13 and U.S. 58 was originally a cloverleaf--it has since been converted to a SPUI. And many cloverleaf interchanges on California freeways are being converted to parclos. In Hampton, Virginia, a cloverleaf interchange between Interstate 64 and U.S. Route 258 has been partially unwound into a partial stack interchange. From now until 2010, four cloverleaf interchanges along I-64/US 40 in St. Louis, Missouri are scheduled to be replaced with SPUIs as part of a major highway renovation project.

A compromise is to add a collector/distributor road next to the freeway; this doesn't eliminate weaving but moves it off the main lanes of the freeway. An example of this is the State Highway 23/I-43 interchange in Sheboygan, Wisconsin, where the exit/entrance roads on and off Highway 23 is two lanes next to the main I-43 freeway on the north and southbound sides of the road.

A few cloverleaf interchanges in California have been rebuilt to eliminate weaving on the freeway while keeping all eight loop ramps, by adding bridges.

Several cloverleafs have been eliminated by adding traffic lights on the non-freeway route. Sometimes, this is even done at the intersection of two freeways, particularly when one freeway terminates at an interchange with another. An example of this is in Lakewood, Washington, at the interchange between Interstate 5 and State Route 512. A visible ramp stub shows that one of the four leaves was removed; thus eliminating an unsafe weave on I-5. In the future, the traffic signal will be replaced by a 2 lane flyover, completing the freeway to freeway interchange once again. [1]

Cloverleafs also occupy much more land than any other kind of interchange (with the possible exception of stack interchanges).

The cloverleaf interchange was not implemented in great numbers in the United Kingdom, owing to these design issues. There were originally three, one in Redditch and two in Livingston. One of the Livingston examples was remodeled in the mid 2000s as part of a public transport project. The major junction of the M11 and A14 at the Girton interchange near the outskirts of Cambridge consists of two cloverleaf loops, making essentially a 'half' cloverleaf interchange. This junction is prone to heavy traffic congestion at peak times, chiefly due to the requirement for westbound A14 traffic to exit the main dual carriageway, traverse one of the cloverleaf loops at slow speeds, then engage in weaving with traffic exiting the M11, in order to continue westward along the A14.

The father of all four-way interchanges, Cloverleaves started appearing in the 1920s, connecting American and German motorways together. In this country they were pencilled into early plans for the motorway network in the 1950s, and the original set of motorway direction signs included a set specifically for use on this type of junction. However, better junction designs had evolved by the time we had two motorways actually crossing each other. No cloverleaf was ever built on the UK network, and today only three exist across the whole country.

Though they exist across the world, they are now widely discredited in most places. Most American states have active policies to remove them from busy routes, mostly because of the weaving problems they create

What bothers me is how can the planners living in the 21st century fail to take note of all these problems that other countries have gone through for decades completely ignore all these and come up with a design that is outdated and unsafe ??

Will Koyembedu model solve that weaving issue?It has 3 loops and 1 is underpass.

Grade Separator on Koyembedu Junction at the intersection of NH 4 and Inner Ring Road

So if they change the kathipara design with 2 loops and other 2 loops can be implemented like koyembedu bridge,I think,it will solve that issue.

Koymebedu bridge follows which model?any name we have?like "modified cloverleaf"....

weaving would still be there. even the one merging from city side (ponamallee towards west) into IRR towards Anna nagar would have to cut across traffic on IRR north that intends to take ponamallee rd east.

but that should not be problem for this interchange. most traffic is along irr. traffic from irr south going to ponamallee west would reduce soon once chennai bypass completes. and one along ponamallee N & S - port traffic could also reduce in the elevated port connectivity road materializes.

point fusionist is making is if a cloverleaf flyover has specific turns that has high traffic then it needs to be avoided. kathipara potentially has such issue. traffic from guindy along anna salai towards IRR north merges just before the one from airport towards anna salai. from pictures this distance looks like about 200m. i think that should be sufficient for vehicles to criss cross. it is not as though we drive at 60 miles per hour. these are city roads and not interchanges for expressways. i am not too bothered.

i think these design are overkill. remember these junctions are all at grade and currently managed through traffic lights.

weaving would still be there. even the one merging from city side (ponamallee towards west) into IRR towards Anna nagar would have to cut across traffic on IRR north that intends to take ponamallee rd east.

but that should not be problem for this interchange. most traffic is along irr. traffic from irr south going to ponamallee west would reduce soon once chennai bypass completes. and one along ponamallee N & S - port traffic could also reduce in the elevated port connectivity road materializes.

point fusionist is making is if a cloverleaf flyover has specific turns that has high traffic then it needs to be avoided. kathipara potentially has such issue. traffic from guindy along anna salai towards IRR north merges just before the one from airport towards anna salai. from pictures this distance looks like about 200m. i think that should be sufficient for vehicles to criss cross. it is not as though we drive at 60 miles per hour. these are city roads and not interchanges for expressways. i am not too bothered.

i think these design are overkill. remember these junctions are all at grade and currently managed through traffic lights.

Consider annasalai to irr flow,we can use the existing loop,
GST to annasalai flow,turning left and going through the underpass like koymbedu design will solve weaving issue, right.Anyway when it enters,still weaving is there.

weaving would still be there. even the one merging from city side (ponamallee towards west) into IRR towards Anna nagar would have to cut across traffic on IRR north that intends to take ponamallee rd east.

but that should not be problem for this interchange. most traffic is along irr. traffic from irr south going to ponamallee west would reduce soon once chennai bypass completes. and one along ponamallee N & S - port traffic could also reduce in the elevated port connectivity road materializes.

point fusionist is making is if a cloverleaf flyover has specific turns that has high traffic then it needs to be avoided. kathipara potentially has such issue. traffic from guindy along anna salai towards IRR north merges just before the one from airport towards anna salai. from pictures this distance looks like about 200m. i think that should be sufficient for vehicles to criss cross. it is not as though we drive at 60 miles per hour. these are city roads and not interchanges for expressways. i am not too bothered.

i think these design are overkill. remember these junctions are all at grade and currently managed through traffic lights.

I think we can not have major design changes at this point since the construction is in advanced stage.

I find that the turning radius, width and the lane interchange zone length as the limiting factors. Volume traffic should be physically measured and precautions have to be taken. Speed restriction is must.

Sudden thought. In case a traffic jam occurs right on the grade separator, how it will be controlled and regularised without the help of traffic cops? Vehicles turning left and vehicles going straight / right from the left lane will bump into each other.

Consider annasalai to irr flow,we can use the existing loop,
GST to annasalai flow,turning left and going through the underpass like koymbedu design will solve weaving issue, right.Anyway when it enters,still weaving is there.

Koyambedu interchange also has weaving issues. However I don't think it will have the same degree of problem as the lane merging might cause in the Kathipara. This is because of the traffic volume pattern. In Koyambedu high traffic lanes like the IRR and PHR have been kept straight and clean, so there is less chance of traffic jams in this plan.

However I would think it is better to have a re-evaloation of Koyambedu plans before it is implemented as there could be better options.

As for the Kathipara, if you check out the Chennai Project Updat ethread ( posts nos arouns 1520 to 1550 ) we had a detailed discussion on the issue. The plan which I think avoids weaving completely, and can be managed in just about the same space without much aded costs is the one below..

Quote:

Features:
1. Takes just about the same space.
2. Would cost just about the same.
3. Gets rid of small loops. ie. more safe especially the Meridian loop which probably is very tight.
4. gets rid of ALL weaving throughout the interchange. !!
5. Only 2 levels

However this might not be applicable to Koyambedu or Padi. It is better to treat each project individually rather than applying the model best suited for one project on another.

Koyambedu interchange also has weaving issues. However I don't think it will have the same degree of problem as the lane merging might cause in the Kathipara. This is because of the traffic volume pattern. In Koyambedu high traffic lanes like the IRR and PHR have been kept straight and clean, so there is less chance of traffic jams in this plan.

However I would think it is better to have a re-evaloation of Koyambedu plans before it is implemented as there could be better options.

As for the Kathipara, if you check out the Chennai Project Updat ethread ( posts nos arouns 1520 to 1550 ) we had a detailed discussion on the issue. The plan which I think avoids weaving completely, and can be managed in just about the same space without much aded costs is the one below..

However this might not be applicable to Koyambedu or Padi. It is better to treat each project individually rather than applying the model best suited for one project on another.